4 wheel low issues

hi , i have a 03 z71 silverado , it just recently had the transfercase and tranny separated and the gaskets replased , about a week ago an today i put it into foor wheel low and i noticed when i start to turn corners in 4L the engine almost seems like it starts to die and the tiresfeel like thelock up it hops foward in very rough way
dose anyone know what could cause this it dose not do it if i put it in awd

Not sure what settings your '03 system has, but this kind of behavior is "normal" for part tiem 4wd systems. In 2H, the front end is completely disconnected. In 4A, the front end is connected, and powered "on demand." In 4H and 4L, the transfer case is "locked" so that the front and rear driveshafts are locked together and have to spin at the same speed. On pavement or other high traction surface, when you turn, the front end has to turn faster than the rear, but it cannot because it is locked at the transfer case. The result is "drivetrain tension" that expresses itself as difficulty turning, bogging in turns, or wheels hopping, or u-joints breaking, or gears breaking. This is why the 4H and 4L settings should only be used in low traction conditions when the wheels have plenty of slip and this tension doesn't build up.